1. Field of the Invention
The present invention relates to a camera with a built-in winder which is capable of automatic film advance, as well as charging the shutter, diaphragm and mirror mechanisms.
2. Description of the Prior Arts
Drive mechanism for use in single-lens reflex cameras are classified broadly into the following two types: (1) A charge-type or force storing type drive mechanism, i.e., when charged, it stores external energy once in a spring and the like as a driving force, and instantaneously discharges the stored driving force to ensure the efficient start-up of diaphragm, mirror and shutter mechanisms for their timely and prompt operation to thereby expose a film. (2) A film advance drive mechanism, i.e., it directly uses external force as a driving force for film wind-up.
In recent years, there have been proposed cameras which use a single film advance motor provided therein as an external energy source to actuate such two types of drive mechanisms for automatically winding a film and charging the diaphragm, mirror and shutter mechanisms. These cameras are more simplified in construction as compared with those which are automatically operated by external forces given to the two types of drive mechanisms from the respective motors.
When, however, film advance and the charge of diaphragm, mirror and shutter mechanisms are performed by a movable member driven by the single film advance motor, the movable member, after charging a charge-type drive mechanism on one side, must be retracted outside the operation path of a drive member in the charge-type drive mechanism, so that the operation of the charge-type drive mechanism may not be impeded. The drive member returns along the operation path under the action of stored force for operation of the charge-type drive mechanism. On the other hand, a film advance mechanism is originally designed to be driven always in one direction to wind a film, requiring no retracting operation. Therefore, prior art cameras are provided with a clutch between a film advance mechanism and a charge-type drive mechanism to release the clutch when film advance has been completed, so that the film advance mechanism may be prevented from following the operation of the charge-type drive mechanism. However, this makes the camera construction complex. In addition, prior art cameras are designed to have part of the charge-type drive mechanism charged simultaneously with film advance, requiring the output force of the motor for use as an external energy source to be sufficiently strong. This, in turn, increases the motor capacity, causing a load balance between the forward and reverse motor rotations to deteriorate, and driving efficiency to decrease.